The invention relates to a mixing faucet for two liquids of different temperatures that comprises a mixing valve, a perforated plate valve with an actuation quantity that determines the volume of an outflow, and at least one rotary actuator mounted in a rotary degree of freedom in relation to a fixed housing, wherein rotation of the at least one rotary actuator adjusts at least a first of two independent coaxial rotational control variables to control the volume or temperature of an outflow.
Mixing faucets with two rotary actuators are known, which adjust two incoming flows by means of one closing valve or one closing and mixing valve for each of the said flows, whose rotational axes include an angle between 60° and 120° or are spaced at a distance to one another. The disadvantage of these mixing faucets is that the quantity and temperature of the outflow can only be adjusted in combination by two gripping movements, whereby the two movements enable fine adjustability. This is achieved by single uniaxial rotary movements rotating through angles of up to more than 360°; this is known by experience as the best actuating movement because it is known to be most safely and confidently controllable.
Mixing faucets are also known with one actuator movable in two degrees of freedom.
DE1198150A and DE2724429A1 describe mixing faucets with an actuator that sets the quantity of outflow by a shift in the direction of the rotational axis and the size ratio of two inflows via a rotational movement of max. 150°. The disadvantage is the limited angle of rotation of 150°, which does not assure fine adjustability. The longitudinal movement is ergonomically even more unfavorable and gives only unsatisfactory results.
DE2636517A1 discloses an actuator with two degrees of freedom. A shift in the direction of the rotational axis switches to adjust either the quantitiy of the outflow or the size ratio of two inflows by rotating the single actuator by max. 180°. The to disclosed design requires two movements for a change of temperature, that is: firstly, the longitudinal movement to switch, then the rotational movement; this is not only cumbersome but also ergonomically implausible and thus unfavorable. Moreover, additional pulling or pushing force is applied during the rotational movement for one of the adjustments in order to maintain the adjusted setting, which makes handling more difficult. Thus, despite the single directly accessible actuator, only one variable is available in direct access. Fine and accurate adjustment is thus not possible due to the limited angle of rotation. The complex valve design with one closing and mixing valve for each inflow is delicate and costly, and the mixing valve is difficult to clean and replace. The entire valve construction is obsolete.
Lever mixer faucets are the most familiar type (for example DE3411447A1, DE2324364A), having a lever handle as the rotary tilting actuator with two degrees of freedom, in which the initial longitudinal movement of a piston valve that is also rotatable is converted into a vertical tilting movement of the lever to adjust the outflow quantity.
It is now state of the art to equip these lever mixing faucets with a ceramic perforated plate mixing valve, whereby the movable perforated plate is in direct rotational contact with the lever actuator. The temperature is adjusted by means of a rotational movement of the lever actuator via the size ratio of two inlet cross sections, and the outflow quantity is adjusted via the size of the inlet cross sections by means of a rotation-dependent tilting movement of the same lever actuator.
In these lever mixing faucets, only tilting angles of less than 30° and angles of rotation of less than 120° are feasible, which is ergonomically inadequate. The combination of two basically single rotational or tilting movements in the same actuator results in an unmanageable and barely controllable three-dimensional movement, which is not capable of intuitive regulation when operated only briefly. The adjustment movement has to be corrected subsequently and as experience shows, it has to be broken down into the two basic movements, although a successful, clear separation of the two is rare. It has become apparent that, for over 90% of people, the two basically independent variables, outflow quantity and temperature, are almost impossible to adjust accurately by means of a combined rotational and tilting movement. Inadvertent maladjustment, such as opening the faucet unintentionally, happens easily merely by knocking against the lever handle, which may even lead to scalding in the worst case.
It is known from DE10347819A1 to provide a mixing faucet without a mixing valve, the mixing faucet having two coaxial rotary actuators in succession. The required high torque can only be applied with levers, even if an intermediate gear is present. Each rotary actuator operates a closing valve for cold or hot water respectively. This does not permit a deliberate clear setting of the temperature or outflow quantity, as the temperature results from the relative angle of rotation of both rotary actuators. Nor are the directions of access either the same or consistent, so that genuine single handed operation (i.e. access with one hand) is ruled out. The angles of adjustment are extremely small due to reduction by the internal crown gear, and this is only slightly and inadequately compensated by the intermediate gear. At the same time, this system increases the differentials in the direction of access. Fine and accurate adjustment is impossible with this principle.
Thermostatic mixers (e.g. DE3118003A1, DE10044684A1, EP0242680A2) have two single-axis rotary actuators, which are widely spaced in an ergonomically unfavorable manner, with access from opposite directions, even though they permit 180° of rotation for the quantity and 360° for the temperature of the outflow. This necessitates two grasping movements and opposite rotational movements, thus ruling out comfortable single-handed operation.
Thermostatic mixers that are partially built into the wall (DE10048041A1) are provided with two coaxial rotary actuators arranged in succession, with a rotational angle of approximately 360° (for the temperature) and just under 90° (for outflow volume control), and can be adjusted from two directions of access lying at least close together. The front rotationally symmetrical rotary actuator for the temperature can be grasped and positioned at the end, the rear rotary actuator for the outflow volume works due to the high torque only via a radial lever, and this does not allow genuine single-handed operation. Both adjustment movements are achievable only by means of dual access, in which the direction of access to the lever changes during the adjustment movement in absolute and, above all, relative terms in relation to the direction of access of the front rotary actuator. Temperature adjustment is more obvious and easier than the adjustment of the outflow volume. This is ergonomically inadequate, as the volume adjustment at the start of the outflow has the highest priority when operating a mixing faucet. Moreover, the built-in thermostat is requires complex installation in the wall, hence is not suitable for the common and by far the most frequent use in visible applications as sink, shower and bath faucets.
An object of the invention is to create a mixing faucet that will allow selective, substantially direct, comfortable, and clear setting of the two target variables, i.e. temperature and quantity of outflow, substantially independently of each other whilst ruling out inadvertent actuation, for example by a mere knock, thus creating the conditions for genuine single-handed operation in a permanent direction of access, also of thermostatic mixers, using proven valve technology at little extra cost.